This invention relates to semiconductor devices and, more particularly, to a device and method for achieving a high speed operation semiconductor device for potential use in oscillators, mixers, logic circuits, radiation sensors, modulators, and other circuit applications.
In recent years high speed semiconductor devices have been developed, and the achievement of even faster devices is a widespread goal. The phenomena of so-called ballistic action, resonant tunneling, hot electron tunneling, and other mechanisms in real and/or theoretical high speed semiconductor devices, are described in the following publications: T. E. Bell, "The Quest For Ballistic Action", IEEE Spectrum, February, 1986; J. M. Poate et al., "Progress Toward A Metal-Base Transistor", IEEE Spectrum, February, 1985; L. F. Eastman, "Ballistic Electrons In Compound Semiconductors", IEEE Spectrum, February, 1986; M. I. Nathan et al., "A Gallium Arsenide Ballistic Transistor?", IEEE Spectrum, February, 1986; Y. Zohta, "Negative Resistance Of Semiconductor Heterojunction Diodes Owing To Transmission Resonance", J. Appl. Phys. 57(6), 1985; T. Sollner et al., "Resonant Tunneling Through Quantum Wells At Frequencies Up To 2.5 THz", Appl. Phys. Lett. 43(6), 1983; T. Sollner et al., "Quantum Well Oscillators", Appl. Phys. Lett. 45(12), 1984; S. W. Kirchoefer et al., " Negative Differential Resistance At 300K In A Superlattice Quantum State Transfer Device", Appl. Phys. Lett. 44(11), 1984; A. Kastalsky et al., "High Frequency Amplification And Generation In Charge Injection Devices", Appl. Phys. Lett. 48(1), January, 1986; M. Heiblum et al., "Tunneling Hot-Electron Transfer Amplifier: A Hot-Electron GaAs Device With Current Gain", Appl. Phys. Lett. 47 (10), 1985; J. R. Barker, "Quantum Theory Of Hot Electron Tunneling In Microstructures", Physika 134B, 1985; Hickmott et al., "Sequential Single-Phonon Emission In GaAs-Al.sub.x Ga.sub.1-x As Tunnel Junctions", Phys. Rev. Lett. 52(23), 1984.
In the last-listed publication, Hickmott et al., there is disclosed a structure which in which there is tunneling current from a heavily doped (n.sup.+) GaAs layer, through an Al.sub.x Ga.sub.1-x As layer into a lightly doped (n.sup.-) GaAs layer in magnetic fields large enough for magnetic freezeout to occur.
It is an object of the present invention to provide a novel device and method for obtaining high speed operation in a semiconductor structure.